Homework Hints

This is one of the best all around sites that I have found. It is titled "The MacTutor History of Mathematics Archive."

http://www-history.mcs.st-and.ac.uk/~history/

This is an award-winning site that links to all sorts of mathematics information.
http://archives.math.utk.edu/

Here is a history of calculating machines with pictures and links:
http://www.webcom.com/calc/main.html

Napier's Bones is an example of a 17th century calculating device:
http://www.maxmon.com/1600ad.htm